On Mon, Mar 07, 2016 at 12:23:28PM +0800, Peter Xu wrote:
> For emulated GIC capabilities, currently only gicv2 is supported. We
> need to add gicv3 in when emulated gicv3 ready. For KVM accelerated ARM
> VM, we detect the capability bits using ioctls.
>
> When probing the KVM capabilities, we cannot leverage existing helper
> functions like kvm_create_device() since QEMU might be using TCG while
> probing (actually this is the case for libvirt probing). So, one
> temporary VM is created to do the probing.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> target-arm/machine.c | 105
> ++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 104 insertions(+), 1 deletion(-)
>
> diff --git a/target-arm/machine.c b/target-arm/machine.c
> index 60bd5c1..ff50411 100644
> --- a/target-arm/machine.c
> +++ b/target-arm/machine.c
> @@ -1,3 +1,5 @@
> +#include <linux/kvm.h>
> +#include <sys/ioctl.h>
> #include "qemu/osdep.h"
> #include "hw/hw.h"
> #include "hw/boards.h"
> @@ -347,7 +349,108 @@ const char *gicv3_class_name(void)
> exit(1);
> }
>
> +static GICCapability *gic_cap_new(int version)
> +{
> + GICCapability *cap = g_new0(GICCapability, 1);
> + cap->version = version;
> + /* by default, support none */
> + cap->emulated = false;
> + cap->kernel = false;
> + return cap;
> +}
> +
> +static GICCapabilityList *gic_cap_list_add(GICCapabilityList *head,
> + GICCapability *cap)
> +{
> + GICCapabilityList *item = g_new0(GICCapabilityList, 1);
> + item->value = cap;
> + item->next = head;
> + return item;
> +}
> +
> +#ifdef CONFIG_KVM
> +/*
> + * This is merely the same as kvm_create_device(). The only
> + * difference is we are using raw fds rather than KVMState, so that
> + * we can use it even without kvm_state initialized.
> + */
> +static int kvm_create_device_fds(int kvm_fd, int vmfd,
> + uint64_t type, bool test)
I don't think we need this helper function. Who else will call it?
Particularly without test==true? Anyway, I think three ioctls directly
called from qmp_query_gic_capability should be OK.
> +{
> + int ret;
> + struct kvm_create_device create_dev;
> +
> + create_dev.type = type;
> + create_dev.fd = -1;
> + create_dev.flags = test ? KVM_CREATE_DEVICE_TEST : 0;
> +
> + if (ioctl(kvm_fd, KVM_CHECK_EXTENSION, KVM_CAP_DEVICE_CTRL) <= 0) {
> + return -ENOTSUP;
> + }
> +
> + ret = ioctl(vmfd, KVM_CREATE_DEVICE, &create_dev);
> + if (ret) {
> + return ret;
> + }
> +
> + return test ? 0 : create_dev.fd;
> +}
> +#endif
> +
> GICCapabilityList *qmp_query_gic_capability(Error **errp)
> {
> - return NULL;
> + GICCapabilityList *head = NULL;
> + GICCapability *v2 = gic_cap_new(2), *v3 = gic_cap_new(3);
> +
> + v2->emulated = true;
> + /* FIXME: we'd change to true after we get emulated GICv3. */
> + v3->emulated = false;
> +
> +#ifdef CONFIG_KVM
> + {
> + /*
> + * HACK: here we create one temporary VM, do the probing,
> + * then release it properly.
> + */
> + int kvm_fd = -1;
> + int vmfd = -1;
> +
> + kvm_fd = qemu_open("/dev/kvm", O_RDWR);
> + if (kvm_fd == -1) {
> + /* KVM may not enabled on host, which is fine. */
> + goto out;
> + }
> +
> + do {
> + /* For ARM, VM type could only be zero now. */
> + vmfd = ioctl(kvm_fd, KVM_CREATE_VM, 0);
> + } while (vmfd == -EINTR);
> +
> + if (vmfd < 0) {
> + goto kvm_fd_close;
> + }
> +
> + /* Test KVM GICv2 */
> + if (kvm_create_device_fds(kvm_fd, vmfd, KVM_DEV_TYPE_ARM_VGIC_V2,
> + true) >= 0) {
> + v2->kernel = true;
> + }
> +
> + /* Test KVM GICv3 */
> + if (kvm_create_device_fds(kvm_fd, vmfd, KVM_DEV_TYPE_ARM_VGIC_V3,
> + true) >= 0) {
> + v3->kernel = true;
> + }
> +
> + close(vmfd);
> +kvm_fd_close:
> + close(kvm_fd);
> + }
> +#endif
> +
> +out:
> + head = gic_cap_list_add(head, v2);
> + head = gic_cap_list_add(head, v3);
> +
> + return head;
> }
> --
> 2.4.3
>
>
